Telecommunications is becoming increasingly important in today's society. In addition to voice traffic, the advent of the Internet has greatly increased the amount of data exchanged over telecommunications lines. For example, many persons access the Internet from home computers. To facilitate such access, a telecommunications central office may utilize a telecommunications chassis that is connected to the home user through telephone lines.
A conventional telecommunications chassis may include a plurality of cards, or processing capability embedded on a physical device, disposed in slots in the chassis. Example cards include devices known as “line cards,” which include functionality that terminates communication at the central office. An example line card is an ADSL line card, which includes the functionality that provides an ADSL connection between a central office and a person's home. The ADSL line card may in turn communicate with another card on the chassis, such as a network interface card. The network interface card may address communications with networks upstream from the central office, performing switching functions.
Conventionally, each chassis includes a plurality of line cards and one or more common cards, such as a network interface card. Because both types of cards occasionally fail, it is desirable to provide some redundancy for the cards. According to one approach, one redundant card is provided for each operating card. However this type of redundancy is expensive. Such redundant systems may allow one card to back up a plurality of others, known as “N:1” redundancy; however, such an approach has disadvantages. According to one approach, a protect bus on the backplane of the chassis is used to connect a line card to a redundant line card. When a failure is detected in the line card, switching routes communication from a user's home across the protect bus to the redundant line card. However, conventionally such redundancy requires a non-generic line card with switching capability to serve as the redundant card. This requires maintaining two different types of cards for each distinct product line, which is expensive and cumbersome.